There are some persons who are sedentary for long periods of time. A particular class of these persons are those who use wheelchairs. Those who are confined to wheelchairs become emaciated in their lower extremities so that they are further subject to discomfort, fatigue, pain, and ultimately ulcers.
There has been a multiplicity of contoured chairs, cushions and seats which have been designed to improve the comfort of those persons required to sit for long periods of time.
Doctors have been troubled with the problems of patients who spend long periods of time in wheelchairs. Those patients who have emaciated lower extremities or paralysis often have little sense of feeing in their posterior, and consequently cannot determine when inadequate circulation is leading to deterioration. Pressure problems initiate at the points on the posterior where the bone structure of the seated patient is close to the supporting surface, such as is in the case of the ischial tuberosities and trochanters. Previous attempts to solve these localized pressure problems have not recognized the importance of proper weight distribution across the surfaces of the gluteal region, and particularly maximum and minimum surface pressures over the various areas. While these concepts are particularly useful for wheelchair users who may have emaciated lower extremities and/or limited sense of feeling in the posterior, these concepts are also useful for others who are sedentary for long periods of time.